Process for spinning proteins



Patented Apro 16, 1946 2,398,625 rnocnss FOR. SPINNING raornms George Stephan de Kadt, Leeuwarden, the Netherlands; vested in the Alien Property Custo- No Drawing. Application February 17, 1939, Se-

rial No. 257,030. In the Netherlands March 1,

2 Claims.

This invention relates to an improved process for producing artificial fibres such as filaments, threads and the like by spinning protein solutions, particularly casein solutions.

Protein solutions coming into consideration for spinning fibres are prepared by dissolving proteins suitable or rendered suitable to this efiect, for instance casein or other animal or vegetable proteins, such as fish proteins and soya protein, in diluted alkaline solution. Moreover inorganic or organic substances may be added to these solutions, which substances influence the spinning process or the products obtained in some way or other. Such a solution is then spun in an acid spinning bath, consisting as generally known of solutions of strong acids, salts and if desired organic substances. Also spinning baths have been proposed, consisting of mixtures of alcohol and organic acids. Since these latter baths are however impractical and uneconomic the first mentioned baths are generally preferred.

It has, however, not sufliciently been realised, that proteins are amphoteric substances maintaining also in strongly acid medium a certain hydration degree and which therefore insufliciently dehydrate in the above-mentioned spinning baths. The result is with such baths 1 that an insufilcient spinning speed is obtained, 2 the stretching of the thread is restricted and 3' the fibre has a very high shrinkage resulting in fibres which after this shrinkage has been completed, may be more than 100% thicker than the fibres obtained during spinning.

Obviously these three drawbacks will not appear in the same degree with all compositions of spinning baths.- Thus the following data were I found by spinning a 16% casein solution:

These figures sufliciently show the drawbacks of the above type of spinning bath and it will be clear that it is of great importance to provide for a spinning bath type having these drawbacks not at all or in much less degree.

By my invention I succeeded in this respect by making use of spinning baths consisting of a solution of organic and/or inorganic salts to, which only such an amount of one or more organic acids has been added, that the pH value of the spinning bath is more than 2 and preferably above 2.7 or even above 3.0. The spinning bath may according to my invention also consist of a solution of organic salts with or without inorganic salts, to which only such an amount of inorganic acid and if desired organic acid is added that the pH value of the spinning bath is more than 2 and preferably above 2.7 or even above 3.0.

Moreover the spinning baths according to the invention may contain organic substances substantially not influencing the pH value, such as for instance alcohol, glycerol, glucose, urea and the like.

Though the pH value of these baths comes very close to the isoelectric point of casein i. e. the point at which the hydration of casein should be a minimum and which corresponds to a pH value of 4.6 to 4.7 I have found by many experiments that besides the low acidity also the salt content is of considerable importance since the spinning bath which for instance only contains organic acid is, without salt, not at all utilisable for spinning or gives very unsatisfactory results.

An example of a spinning bath for use according to my invention is an aqueous solution con- Shrinkage Maxl- Mink of the s inningbatb Tern 8552?; 11 $831111? as we e:

rcen 0 obtained obtained {EB length spun 6 7 ti id C. M/mln. Percent ace cac 20%61182804 The fibres so obtained were of very good quality.

spinning a solution of casein in dilute alkali into 10 an aqueous spinning bath having a pH higher than 2 and containing lactic acid, a. lactate and an inorganic salt in solution therein.

2. A process for the production of protein products of low shrinkage characteristics comprising spinning a solution of protein material in dilute alkali into an aqueous spinning bath containing 5% of lactic acid, 5% of sodium lactate and 15% of magnesium sulphate in solution therein.

GEORGE STEPHAN DE KADT. 

